#1317 Special Case Pattern (#1624)

* #1317 Add Special Case Pattern

To focus on pattern itself, I implement DB and
maintenance lock by the singleton instance.

* #1317 Add special cases unit tests

Assert the logger output
(ref: https://stackoverflow.com/a/52229629)

* #1317 Add README.md

Add Special Case Pattern README

* #1317 Format: add a new line to end of file

Co-authored-by: Subhrodip Mohanta <subhrodipmohanta@gmail.com>

pom.xml

@@ -200,6 +200,7 @@
         <module>factory</module>
         <module>separated-interface</module>
         <module>data-transfer-object-enum-impl</module>
+        <module>special-case</module>
     </modules>
 
     <repositories>